A TI{KozakGAL4} DNA cassette has been inserted into Psn, replacing the coding sequence (coordinates of deleted sequence are 3L:20432839..20435060 , release 6 genome). This results in a simultaneous knock-out of Psn plus a knock-in of GAL4 that is expected to be expressed under the control of the endogenous regulatory sequences of Psn (predicted to gene trap all annotated transcripts of the gene). The upstream end of the deletion associated with the insertion is 478 bp from the annotated TSS of the Las gene on the opposite strand and may affect its expression. The TI{KozakGAL4} cassette was inserted via the CRISPR/Cas-9 drop-in technique, using a dsDNA donor vector with homology arms of length 200bp. The sgRNA sequences used to target the gene were: GAACGAACGCACACCACTGATGG and TATATAAACTTGAAAAGACAAGG.